According to a currently known adaptive modulation and coding (AMC) technology, in a downlink, a terminal device can calculate a channel quality indicator (CQI) value of the current downlink, and can transmit the CQI value to a network device, so that the network device adjusts, according to the CQI value fed back by the terminal device, a downlink Modulation and Coding scheme (MCS) of the user to complete downlink adaptation.
However, with the technical development, for example, in a sparse code multiple access (SCMA) technology or an orthogonal frequency division multiplexing (OFDM) technology, a plurality of terminal devices is already allowed to reuse a same time-frequency resource to perform data transmission.
In this case, the CQI value obtained according to the AMC technology can reflect only general interference on the time-frequency resource reused by the plurality of terminal devices, but cannot reflect specific interference on each terminal device in the plurality of terminal devices reusing the time-frequency resource. Therefore, the AMC technology is no longer applicable to adjustment of a Modulation and Coding scheme for terminal devices that reuse a same time-frequency resource to perform data transmission.